Glaucoma is a disease of the eye which is characterized by a progressive loss of visual field due to irreversible damage to the optic nerve. If untreated, this condition can result in blindness. This loss of visual field, in one form of primary open angle glaucoma, that is, chronic primary open angle glaucoma, hereinafter POAG, is associated with a sustained increase in the intraocular pressure (IOP) of the diseased eye. In addition, elevated intraocular pressure without visual field loss, or ocular hypertension, can be indicative of the early stages of POAG.
There are a number of therapies that target reducing the elevated IOP associated with ocular hypertension or POAG. The most common feature the topical administration of a beta adrenergic antagonist (beta-blocker) or a muscarinic agonist. These treatments, while effective in lowering IOP, can also produce significant undesirable side effects.
Another less common treatment for ocular hypertension or POAG is the systemic administration of carbonic anhydrase inhibitors; however, this therapy can also bring about unwanted side effects, such as nausea, dyspepsia, fatigue, and metabolic acidosis. Topical administration of carbonic anhydrase inhibitors can be used to control IOP with a reduced risk of encountering the aforementioned systemic side effects. U.S. Pat. Nos. 5,153,192; 5,240,923; 4,797,413; 5,308,863; and EPO 91/452,151A1 disclose topically dosed sulfonamides which lower IOP by inibiting carbonic anhydrase.